The present invention relates to a semiconductor fabrication apparatus management system, an abnormality factor extraction method of a semiconductor fabrication apparatus, and a management method of the same.
A semiconductor fabrication process is required to hold a response variable as a result of the process at a predetermined desired value. For example, a thin film stacking process is required to hold a film thickness as a response variable at a predetermined desired value. Also, an exposure process is required to hold a dimensional value as a response variable within an allowable range with respect to a design value. However, a semiconductor fabrication apparatus may fluctuate a response variable owing to disturbance. In the exposure process, for example, the exposure amount may fluctuate in accordance with the state of an illuminating optical system or the state of a reticle for transferring circuit patterns, thereby fluctuating the dimensional value. This fluctuation in response variable results in a defective product, and decreases the yield of the semiconductor fabrication process.
A semiconductor fabrication process measures various physical amounts by response variable monitoring called QC (Quality Control) when the process is executed. For example, the exposure process measures QC values such as a resist dimensional value and final element dimensional value. Also, various sensors monitor the interior of a semiconductor fabrication apparatus to check whether the apparatus is normally functioning. A semiconductor fabrication apparatus management system like this is called an EES (Equipment Engineering System), and the monitored internal data of the apparatus is called EES data. For example, the EES acquires several hundreds of kinds of EES data such as the exposure amount, focusing value, and developer temperature from an exposure apparatus.
APC (Advance Process Control) which controls a semiconductor fabrication apparatus on the basis of a response variable is performed to hold the response variable constant. In the exposure process, for example, APC controls the exposure amount to hold the resist dimensional value measured as a QC value constant. The exposure amount and resist dimensional value have an almost linear relationship. Therefore, if it is detected from the QC value that the resist dimensional value tends to exceed an allowable range, APC controls the exposure amount so as to decrease the resist dimensional value.
If a QC value fluctuates in a process which performs no APC, an abnormality factor having fluctuated the QC value in an apparatus can be specified by analyzing the correlation between the QC value and EES data (e.g., patent reference 1). However, a process which performs APC holds a QC value constant, and hence cannot specify an abnormality factor in an apparatus even by analyzing the correlation between the QC value and EES data. If this abnormality factor is left uncorrected, it exceeds the control limit of APC and appears as an unexpected defect.
Japanese Patent Laid-Open No. 2004-186445